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What are glucose spikes?

How increases in your blood sugar levels impact weight loss

Typically, the term ‘glucose spike’ was referred to diabetics who had to worry about their blood sugar levels.

However, the term has recently become meaningful to other individuals as well.

Dr silvia  fonda

“Maintaining control of blood sugar levels is more important than many people realise.
This article outlines some of my tips for keeping our blood glucose within a safe range.”
- Silvia Fonda, registered nutritionist

Keep reading to learn what glucose spikes are, how they can be managed, and how they can impact weight loss.

Medically reviewed by Dr. Caroline Fontana Written by Silvia Fonda Last reviewed 17-06-2024

What are glucose spikes?

Glucose spikes essentially refer to quick increases in your blood sugar levels. They are mostly caused by our diet choices, but can also be impacted by certain kinds of exercise.

Our blood sugar levels go up and down throughout the day. It’s normal to experience increases and decreases in your blood sugar every time you eat and in between meals.

However, blood glucose levels that are continually too high or that spike too often can be damaging, especially long-term.

Glucose spikes also come with dips - you experience fatigue, or a ‘crash’, when your blood sugar levels go from very high to very low.

This concept can be visualised as a ‘blood sugar roller coaster’. Large imbalances in your blood sugar can lead to:

  • cravings
  • irritability
  • anxiety
  • dizziness
An infographic depicting a ‘blood sugar rollercoaster’

Keeping your blood sugar levels within an optimal zone is not only better for your overall health - it will make weight loss easier to accomplish too.

What are the symptoms of a glucose spike?

Unless you’re able to measure your blood sugar levels, how can you know if you’re experiencing glucose spikes?

The following signs may indicate that your blood sugar is increasing rapidly throughout the day:

  • you feel fatigued even though you sleep enough
  • your energy levels vary a lot throughout the day
  • you rely on coffee and tea for energy
  • you experience food cravings
  • you often feel very thirsty
  • you wake up randomly in the night on a regular basis
  • you experience headaches or mood swings
  • you feel anxious or irritable when you go a long time without eating

What are the risk factors of glucose spikes?

Glucose spikes cause inflammation in the body. When these spikes happen often, they contribute to atherosclerosis (thickening or hardening of the arteries) and a degeneration of the cells responsible for releasing insulin.

All these factors are linked with an increased chance of developing:

  • type 2 diabetes
  • cardiovascular disease
  • certain cancers

Higher blood glucose levels have also been linked to an increased risk of developing dementia later in life.

The effect of glucose spikes on weight loss

High glucose levels cause high insulin levels, which keep the body in fat storage mode rather than fat burning. When we decrease our blood glucose level, our insulin levels drop too. Insulin reduction is essential for weight loss.

Therefore, if you experience frequent blood glucose spikes, it will be harder to lose weight - even if you are eating in a calorie deficit.

What causes glucose spikes?


Every time we eat our glucose levels are affected. Our bodies break down the food in our stomachs to turn it into energy, causing the amount of glucose in our blood to increase.

After blood sugar levels rise, the pancreas gets a signal to start releasing insulin. This helps the cells to absorb some of the sugar, bringing glucose levels down again.

White slices of bread in a basket

Carbohydrates and sugary foods are most responsible for causing sharp glucose spikes after eating. This is because carbs are broken down into simple sugars once consumed.


Exercise can also be responsible for changes in glucose levels.

In general, being active has been shown to:

  • reduce long-term health risks
  • improve insulin sensitivity
  • help maintain a steady glucose range

However, certain types of exercise can cause glucose spikes. Intense workouts (such as sprints, competitive sports, and weight training) cause you to release glucose to provide your body with extra energy.


It is normal, in healthy individuals, for the blood sugar to go up and down while sleeping.

Between the hours of 4.00 a.m. and 8.00 a.m., there is a normal increase in blood glucose called the “dawn phenomenon” which effectively is like a natural alarm clock.

Some people, however, may experience glucose spikes at other times of the night, especially if they have difficulty falling asleep or staying asleep.

Other symptoms of irregular glucose spikes at night include:

  • frequent need to urinate
  • disturbed sleep
  • feeling thirsty
  • headache
  • nausea

How do you prevent glucose spikes?

Preventing spikes from diet

Here are some helpful dietary tips to prevent glucose spikes and maintain steady energy throughout the day:

  • Eat a protein-rich and low-carb breakfast and make sure you don’t skip your first meal of the day!
  • Include fibre, protein and fats at every meal or snack. Following the Mediterranean diet can help you achieve this.
  • Start your meals with vegetables which are high in fibre. This will help to slow down the conversion of carbs into sugar.
A prohibition sign next to a pile of white sugar

  • Reduce all forms of sugar - glucose, sucrose, fructose, honey, maple syrup, fruit juice, etc. Make sure to read nutrition labels as sugars are found in the majority of packaged/processed foods.
  • Cut down on simple and processed carbs such as white rice, pasta, and white bread. Opt for whole-grain versions instead.
  • Minimise caffeine, which can also contribute to the blood sugar roller coaster by increasing adrenaline which ‘pulls’ sugar from the fat cells into the bloodstream.
  • Include more healthy fats like nuts, coconut oil and avocados.
  • Avoid or limit alcohol.

Going for a quick 15-minute walk after meals will also reduce the size of your glucose spike.

Preventing spikes from exercise

To prevent a sharp glucose spike due to exercise:

  • Choose moderate-intensity exercise with light weights and high repetitions when lifting weights.
  • Opt for longer sessions of moderate exercise instead of high-intensity intervals and sprints when doing cardio.
  • Exercise later in the day, as we already have a natural glucose spike between 4-8 a.m.
  • Avoid eating too many carbohydrates before exercise, and instead choose yoghurt with nuts or peanut butter, or hummus with vegetables.

Preventing spikes from sleep

Lastly, to prevent glucose spikes when sleeping:

  • Try and maintain a steady blood glucose during the day by eating regularly following the dietary tips we have discussed earlier in this article.
  • Make sure that your evening meal contains plenty of fibre, protein and a lower amount of carbohydrates.
A balanced meal containing plenty of fibre and healthy fats

Avoid sugary snacks after dinner or close to bedtime.

Make sure you are well hydrated before going to sleep by consuming water throughout the day.

Main takeaways

While it’s normal for our blood glucose levels to go up and down throughout the day, limiting sharp glucose spikes is better for our overall health and makes weight loss easier.

Ways of preventing sharp glucose spikes
From diet From exercise
  • Avoid eating large portions of refined carbs (white bread, rice, potatoes, cereals)
  • Include protein, fibre, and fats at every meal/snack
  • Reduce or cut out any added sugar in your diet
  • Stick to moderate exercise instead of anything intense
  • With weights, pick a lower weight and perform more repetitions
  • Go for a quick 15-minute walk after meals

Further reading

Healthy cake baking for dieters

Understanding food cravings and how to tackle them Healthy cake baking for dieters

Reviewed by Dr. Caroline Fontana
A complete guide to binge eating: what you need to know

Understanding food cravings and how to tackle them A complete guide to binge eating: what you need to know

Reviewed by Dr. Caroline Fontana
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